1. Field of the Invention
The present invention relates to an electrolytic solution for a fluoride ion battery in which a reaction between fluoride ions and a solvent is suppressed.
2. Description of Related Art
As a battery having high voltage and high energy density, for example, a Li ion battery is known. The Li ion battery is a cation-based battery using a reaction between Li ions and a positive electrode active material and a reaction between Li ions and a negative electrode active material. On the other hand, as an anion-based battery, a fluoride ion battery using a reaction of fluoride ions is known. For example, US 2012/0164541 A discloses a fluoride ion battery including: an anode; a cathode; an electrolyte including a fluoride salt; and a predetermined additive.
US 2012/0164541 A describes that an ionic liquid is used as a solvent of an electrolytic solution and that 1-methyl-1-propylpiperidinium (MPP) cation, butyltrimethylammonium (BTMA) cation, or 1-butyl-1-methylpyrrolidinium (BMP) cation is used as a cation of the ionic liquid.
Since the stability of fluoride ions is low, there is a problem in that an activity of fluoridating an active material is low. In other words, due to their high reactivity, fluoride ions react with other materials (in particular, an electrolytic solution) before reacting with an active material. Therefore, there is a problem in that the fluoride ions may not react with the active material sufficiently.